枚举类

1.什么是枚举

/*
一 . 枚举类的定义:
     1.枚举类的理解 : 类的对象是有限的 , 确定的,
     2.当需要定义一组常量时,强烈建议用枚举类
     3,如果枚举类中只有一个对象, 则可以作为单例模式的实现方式

二. 定义枚举类
    1.jdk5之前:自定义枚举类
    2.jdk5之后:可以使用enum关键字定义枚举类
 */

2.枚举类的使用

3.自定义枚举类

public class EnumTest1 {
    public static void main(String[] args) {
       Season spring = Season.SPRING;
        System.out.println(spring);//Season{seasonName='春天', seasonDesc='春暖花开'}
    }
}

//自定义枚举类
class Season{
    //1.声明Season对象的属性:private final修饰
    private final String seasonName;
    private final String seasonDesc;

    //2.私有化构造器
    private Season(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonDesc;
    }

    //3.提供当前枚举类的多个对象 (类似于接口中的常量)
    public static final Season SPRING = new Season("春天","春暖花开");
    public static final Season SUMMER = new Season("夏天","夏日炎炎");
    public static final Season AUTUMN = new Season("秋天","秋高气爽");
    public static final Season WINTER = new Season("冬天","冰天雪地");

    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }

    @Override
    public String toString() {
        return "Season{" +
                "seasonName='" + seasonName + '\'' +
                ", seasonDesc='" + seasonDesc + '\'' +
                '}';
    }
}

4.使用enum关键字定义枚举类

/*
使用Enum 关键字定义枚举类
定义的枚举类默认继承于java.langEnum类
 */
public class EnumTest2 {
    public static void main(String[] args) {
        Season1 season1 = Season1.SPRING;
        System.out.println(season1.toString());
        System.out.println(season1.getClass().getSuperclass());//class java.lang.Enum
    }
}
//使用Enum 关键字定义枚举类
enum Season1{

    //1.提供当前枚举类的多个对象 (类似于接口中的常量) : 多个对象之间用","隔开
    SPRING("春天","春暖花开"),
    SUMMER("夏天","夏日炎炎"),
    AUTUMN("秋天","秋高气爽"),
    WINTER("冬天","冰天雪地");

    //1.声明Season对象的属性:private final修饰
    private final String seasonName;
    private final String seasonDesc;

    //2.私有化构造器
    private Season1(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonDesc;
    }


    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }

    @Override
    public String toString() {
        return "Season1{" +
                "seasonName='" + seasonName + '\'' +
                ", seasonDesc='" + seasonDesc + '\'' +
                '}';
    }
}

5.枚举类的主要方法

6.枚举类实现接口

public class EnumTest3 {
    public static void main(String[] args) {
        Season2 spring = Season2.SPRING;
        System.out.println(spring.toString());
        System.out.println(spring.getClass().getSuperclass());//class java.lang.Enum
        System.out.println("***********************************************");
        Season2[] values = Season2.values();
        for (int i = 0; i < values.length; i++) {
            System.out.println(values[i]);
            values[i].show();
        }
    }
}

interface info{
    void show();
}
enum Season2 implements info{

    //枚举类实现接口
    //1.重写一次show()
    /*@Override
    public void show() {

    }*/
    //2.每个对象重写一个show()
    SPRING("春天","春暖花开"){
        @Override
        public void show() {
            System.out.println("我是春天");
        }
    },
    SUMMER("夏天","夏日炎炎"){
        @Override
        public void show() {
            System.out.println("我是夏天");
        }
    },
    AUTUMN("秋天","秋高气爽"){
        @Override
        public void show() {
            System.out.println("我是秋天");
        }
    },
    WINTER("冬天","冰天雪地"){
        @Override
        public void show() {
            System.out.println("我是冬天");
        }
    };
    //1.声明Season对象的属性:private final修饰
    private final String seasonName;
    private final String seasonDesc;

    //2.私有化构造器
    private Season2(String seasonName, String seasonDesc) {
        this.seasonName = seasonName;
        this.seasonDesc = seasonDesc;
    }
    public String getSeasonName() {
        return seasonName;
    }

    public String getSeasonDesc() {
        return seasonDesc;
    }

    @Override
    public String toString() {
        return "Season2{" +
                "seasonName='" + seasonName + '\'' +
                ", seasonDesc='" + seasonDesc + '\'' +
                '}';
    }
}